Manufacture of powders of copper and copper alloys



United States Paten 1. 2,870,485 MANUFACTURE OEPOWDERS or COPPER AND COPPER ALLOYS' William panoram -London, England; -assignor:t F. W. Berk & Company Limited; London, England, a British company No Drawing. .Apjplia'tionJiine 26, 1936 Serial'No. 593,835 Claims priority, application Great'Bi'itain October28, 1955 6 Claims. (c1; 18'-'4 7'.3)'

This invention relates to themanufactu're' of copper powders having a low apparent density.

Copper powders of low apparentdensity'are at present made either by electrolysis or by reduction of agglomerates of copper oxide, which yield "a sponge-like mass having the requisite properties. The shape" ofthe particles madeby electrolysis'is dendritic. A copper of low apparent density is essential for the production of sintered articles, having a considerable and controlled porosity, suchas self-lubricating bearings, as the lowapparent density of the powder as it is filled into the mould permits considerable pressing and this is accompanied by the development of suflicient green strength in the compact to enable it to be handled between the press and the sintering furnace. It should be noted that a fine tin powderis often mixed with the copper prior t'o'it's being pressed and alubricant, such as zinc stearate, is also employed to facilitate pressing and add green strength to the compact.

Itis an objectofthe present invention to provide an improved process for producing copper powders having a low apparent density using a process involving atomisation of the molten metal.

However, if copper is atomised in an air jet under the usual conditions a somewhat spherical powder is obtained which has a high apparent density, i. e. the percentage of voids in the powder as poured into a mould is relatively low and even copper atomised bya jet of water had an apparent density of about 3.8-3 grnJc'c.

It has now been found that these difficulties can be overcome if to the copper there is added a small proportion of one or more of the metals hereinafter specified and if the atomisation is effected by water.

Accordingly, the present invention provides a process for the manufacture of a copper powder having a low apparent density wherein molten copper containing a small proportion of one or more of the metals magnesium, calcium, lithium, zirconium and titanium is atomised by means of an aqueous liquid, such as water.

Of the metals specified magnesium is preferred, and preferably it is used in a proportion of at least 0.2% by weight of the copper. Calcium is preferably used in a proportion of at least 0.5%, lithium 'at' least 0.2% and zirconium at least 0.5%, by weight of the copper.

The following examples illustrate how the process of F the invention may be carried into effect.

(1) Copper was thoroughly deo-xidised by poling with a green stick, various proportions of magnesium were added and the melt covered with a layer of charcoal and atomised in the apparatus described in United Kingdom specification No. 553,672 using a water pressure of 1200 is the time taken for 50 gms. of the powder to flowthrough a 60 funnel having an orifice of 0.176" diameter at its lower end, and in the screen analysis measurements percent on 100 means the percentage retained on a 100 mesh B. S. S. sieve, percent 100/200 means the percentage passing a 100 mesh B. S. S. sieve but not passing a 200 mesh B. S. S. sieve, percent 200/300 means the percentage passing a 200 mesh B. S. S. sieve but not passing a 300 mesh B. S. S. sieve, and percent through 300 means the percentage passing a 300 mesh B. S. S. sieve.

Table I Percent Mg in copper: 0.7 0. 5 0.35 0.25 0.2 0

Percent 011 in powder.... 98. 48 99. 99. 42 99. 4 8 99. 24 99-83 Percent Mg in powder. 0.68 0. 43 0.52 0.21 0.19 nil Percent Oxygen content 0. 06 0. 06 0.03 O. 16 0. 11 Flow rate in secs 20 18 16 14 15.8 14. 2 A arent dcnsit grns.

n 1.5 1. 52 1. 7 2. 07 3. 0 a. 84 Screen analysis: I

Percent n 100 trace trace trace trace ml n11 Percent 100/200 21. 27. 5 18.-2 21.3 14. 2 33. 8 Percent 200/300. 18. 6 22.0 17. 4 18.9 16. 4 20. 4 Percent through 300. 59. 7 50.5 64. 4 59.8 69. 4 45. 8

-(2) Example 1 was repeated but using various proportions of calcium instead of magnesium.

The results are shown in Table II.

Table II Percent 0a in co'pper 0 7 I 0.5 l 0.35 0.25

Percent Cu in powder..- 98. 88 99.3 99. 52 Percent Ca in powder 0. 34 0. 81 0.22 Percent Oxygen content. 0.09 0. 14 0.15 Flow rate'in secs 9.6 8. 8 7. 0 7. 3 Apparent-density, gms./cc 1. 69 2. 04 3.1 3. 41 Screen analysis:

Percent on 100 Trace Trace Trace Trace Percent 100/200 29. 17. 7 ;l6. 5 14. 9

Percent 200/300..." 23. 6 18.6 20. 3 28. 2

Percent through 47. 2 63.7 63. 2 56. 0

3) Example 1 was repeated but using various proportions' of lithium instead of magnesium. The results are shown in Table III.

Table 111 Percent Li in copper u 0.5 0.35 0.2

Percent .Cu in powder '98. 96 99. 99. 16 Percent Li in powder 0. 42 0. 30 0. 16 Percent Oxygen content. 0.31 0.01 0. 22" Flowrate in sccs t 14,0 1-3. 9 v 10.3 Apparent density, gms./cc 1 2.0 2. 36 Screen analysis:

Percent on 0.3 0.2 trace Percent 100/200. 29.2 25. 6 28. 8

Percent 200/300 21. 5 19. 0 20. 7

Percent through 300 49. 0 55. 2 50. 5

asraass various proportions Table IV Percent Zr in copper 1.2 0.7 a 0.2

Percent Cu in powder 98.1 Percent Zr in powder 0.9 Percent Oxygen content 0. 16 Flow rate in secs 13. 7 Apparent density, gmsJcc 1. 85 1 Screen analysis:

Percent on 100 trace Percent 100/200 23. 1

Percent 200/300 1S. 7

Percent through 300 58. 2

-(5) Example 1 was repeated using various proportions of titanium instead of magnesium.

The results are shown in Table V.

Table V Percent 'li in copper "i 1.2 i 0.7 0.5

Percent Cu in powder 98. 67 98. 77 99.3 Percent Ti in powder 0.96 0. 00 0. 43 Percent Oxygen content 0.09 0. 04 0.08 Flow rate in secs 27. 0 16. 4 l9. 2 Apparent density, gins/cc. 1. 99 2. 77 3. 0 Screen analysis:

Percent on 100 0.1 trace 0.1

Percent 100/200.. 34. S 12. 2 23. 2

Percent 200/300 23. 4 14. 7 19. 0

Percent through 300 41. 7 73. 1 57. 7

What I claim is:

1. A process for the manufacture of a copper powder of low apparent density which comprises incorporating with substantially pure copper such a small proportion of a metal selected from the group consisting of magnesium, calcium, lithium, zirconium and titanium that the copper remains substantially pure and in such amount as to effectively cause the conversion of a molten mass of the resultant copper composition subjected to atomization by an aqueous liquid to a copper powder of low apparent density suitable for the production of sintered articles, and then atomizing a molten mass of such resultant copper composition by means of such aqueous liquid to convert the same into a copper powder of low apparent density containing at least approximately 98% of copper and less than approximately 1% of said incorporated metal.

2. A process for the manufacture of a copper powder of low apparent density which comprises incorporating with substantially pure copper such a small proportion of a metal selected from the group consisting of magnesium, calcium, lithium, zirconium and titanium that the copper remains substantially pure and in such amount as to effectively cause the conversion of a molten mass of the resultant copper composition subjected to atomization by water to a copper powder of low apparent density suitable for the production of sintered articles, and then atomizing a molten mass of such resultant copper composition by means of water to convert the same into a copper powder of low apparent density containing at least approximitely 98% of copper and less than approximately 1% of said incorporated metal.

3. A process for the manufacture of a copper powder of low apparent density which comprises incorporating with substantially pure copper at least approximately 0.2% by weight of magnesium calculated on the weight of the copper but not in such quantity as to provide more than approximately 1% of magnesium in the copper powder of low apparent density whereby the magnesium is in sufl'icient amount to efiectively cause the conversion of a molten mass of the resultant copper composition subjected to atomization by means of an aqueous liquid to a copper powder of low apparent density but not in such amount as to substantially affect the purity of the copper in such powder, and then atomizing a molten mass of such resultant composition by means of such aqueous liquid to convert the same into said copper powder of low apparent density.

4. A process for the manufacture of a copper powder of low apparent density which comprises incorporating with substantially pure copper at least approximately 0.5% by weight of calcium calculated on the weight of the copper but not in such quantity as to provide more than approximately 1% of calcium in the copper powder of low apparent density whereby the calcium is in suftlcient amount to efiectively cause the conversion of a molten mass of the resultant copper composition subjected to atomization by means of an aqueous liquid to a copper powder of low apparent density but not in such amount as to substantially affect the purity of the copper in such powder, and then atomizing a molten mass of such resultant composition by means of such aqueous liquid to convert the same into said copper powder of low apparent density.

5. A process for the manufacture of a copper powder of low apparent density which comprises incorporating with substantially pure copper at least approximately 0.2% by weight of lithium calculated on the weight of the copper but not in such quantity as to provide more than approximately 1% of lithium in the copper powder of low apparent density whereby the lithium is in sufficient amount to effectively cause the conversion of a molten mass of the resultant copper composition subjected to atomization by means of an aqueous liquid to a copper powder of low apparent density but not in such amount as to substantially affect the purity of the copper in such powder, and then atomizing a molten mass of such resultant composition by means of such aqueous liquid to convert the same into said copper powder of low apparent density.

6. A process for the manufacture of a copper powder of low apparent density which comprises incorporating with substantially pure copper at least approximately 0.5% by weight of zirconium calculated on the weight of the copper but not in such quantity as to provide more than approximately 1% of zirconium in the copper powder of low apparent density whereby the zirconium is in sufiicient amount to effectively cause the conversion of a molten mass of the resultant copper composition subjected to atomization by means of an aqueous liquid to a copper powder of low apparent density but not in such amount as to substantially affect the purity of the copper in such powder, and then atomizing a molten mass of such resultant composition by means of such aqueous liquid to convert the same into said copper powder of low apparent density.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROCESS FOR THE MANUFACTURE OF A COPPER POWDER OF LOW APPARENT DENSITY WHICH COMPRISES INCORPORATING WITH SUBSTANTIALLY PURE COPPER SUCH A SMALL PROPORTION OF A METAL SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM CALCIUM, LITHIUM, ZIRCONIUM AND TITANIUM THAT THE COPPER REMAINS SUBSTANTIALLY PURE AND IN SUCH AMOUNT AS TO EFFECTIVELY CAUSE THE CONVERSION OF A MOLTEN MASS OF THE RESULTANT COPPER COMPOSITION SUBJECTED TO ATOMIZATION BY AN AQUEOUS LIQUID TO A COPPER POWDER OF LOW APPARENT DENSITY SUITABLE FOR THE PRODUCTION OF SINTERED ARTICLES, AND THEN ATOMIZING A MOLTEN MASS OF SUCH RESULTANT COPPER COMPOSITION BY MEANS OF SUCH AQUEOUS LIQUID TO CONVERT THE SAME INTO A COPPER POWDER OF LOW APPARENT DENSITY CONTANING AT LEAST APPROXIMATELY 98% OF COPPER AND LESS THAN APPROXIMATELY 1% OF SAID INCORPORATED METAL. 